Prophylactic dental paste compositions comprising zirconium silicate and tin dioxide



United States Patent Office 3,378,445 PRGPHYLACTIC DENTAL PASTECOMPOSITIONS CQMPRISENG ZIRCONEUM SILICATE AND TIN DIOXIDE Joseph C.Muhler, Indianapolis, Ind., assignor to Indiana University Foundation,Indiana Memorial Union, Bloomington, Ind., a not for profit corporationof Indiana No Drawing. Continuation-impart of application Ser. No.374,257, June 11, 1964. This application June 17, 1966, Ser. No. 558,270The portion of the term of the patent subsequent to June 21, 1983, hasbeen disclairncd 17 Claims. (Cl. 167-93) This is a continuation-in-partof applicants co-pending United States patent applications entitledCleaning and Polishing Agent for Dental Prophylaxis, Ser. No. 374,- 257,filed June 11, 1964, and Prophylactic Dental Paste CompositionsComprising Zirconium Silicate, now U.S. Patent No. 3,257,282.

The present invention relates to a new composition for cleaning andpolishing teeth by dental prophylaxis and more specifically to a dentalprophylaxis composition comprising a mixture of zirconium silicate(ZrSiO and tin dioxide (SnO While Sn has various chemical names [e.g.,tin dioxide, stannic oxide, tin (IV) oxide, and tin oxide], forconsistency, the name tin dioxide is used throughout this application.

Dental plaque, food particles, exogenous stains, and other tooth surfacepigmentation can be removed, to varying degrees, from teeth by means ofa suitable dentifrice and toothbrush, as in ordinary daily brushings.Some enamel stains and pigmentation, however, are much too resistant tothe abrasives found in conventional dentifrice formulations. As aresult, dentists must perform a prophylaxis in order to remove not onlydental calculus (tartar) but the accumulated stains not satisfactorilyremoved by the daily use of a dentifrice. Most frequently, when either adentifrice or the common cleaning and polishing agents used to perform aprophylaxis are employed, the teeth may be cleaned, but they exhibit alow luster or polish. For good dental est'hetics, clean teeth with ahigh luster are desired, and it would be desirable to provide a cleaningand polishing agent capable of accomplishing these results.

The problems encountered in the relatively infrequent use of a cleaningand polishing agent in a prophylactic paste, for example a prophylaxisperformed once or twice a year, are much different than the problemsencountered in the use of a cleaning and polishing agent as aconstituent of a dentifrice for use two or three times a day, eventhough the desired end result of cleaning and polishing of enamel may bethe same. Obviously, it is possible to use a more highly abrasive agentin a prophylactic paste than in a daily brushing with a conventionaldentifrice. However, care must be taken in both cases to avoid excessiveoral hard tissue loss at the expense of cleaning action. In general, ithas been assumed that in attempting to remove the more diflicult formsof stain (e.g., tobacco, green, stannous fiouride, silver nitrate, etc.)there must be a major compromise between cleaning and tooth structureloss, or, in other words, that, in order to have maximum removal ofthese more difiicult stains and/or pigmentations, tooth structure mustbe sacrificed. It would be desirable to provide a cleaning and polishingcomposition for dental prophylaxis which effectively removes even themost difficult enamel stains and pigmentation while minimizing hardtooth structure loss due to abrasion.

Another factor which should be considered in the development of asuitable prophylaxis is the ability to polish the teeth to a highluster, that is, to achieve smooth and 3,378,445 Patented Apr. 16, 1968highly lustrous enamel surfaces. Highly polished surfaces apparently areless receptive to retention of plaque and oral debris, and this factoris one of the motivating reasons for developing a cleaning and polishingagent which not only cleans effectively but which produces anexceptionally good luster. However, good luster heretofore could not beachieved without sacrificing cleaning or increasing abrasiveness.

Little, if any, relationship appears to exist either between thecleaning and the polishing abilities of dental abrasives or between theabrasiveness and the ability of the abrasive to produce a smooth toothsurface. For example, levigated alumina is an excellent polishing agentwhich produces a very smooth and shiny surface, but it is so abrasivethat resultant tooth structure loss precludes its recomendation for use.Precipitated chalk, on the other hand, cleans fairly well but produces arough tooth surface. Dicalcium phosphate is relatively unabrasive, butit fails to effectively polish. A mixture of insoluble sodiummetaphosphate and tricalcium phosphate is a fairly effective polishingagent, but the combination is not a particularly good cleaning agent.The most common agent used in current day dental prophylaxis is flour ofpumice. This agent is a fair cleaner, but it is highly abrasive andproduces an exteremely poor polish. In fact, recent studies have shownthat the resulting tooth surface is so rough after being treated withflour of pumice that the occurrence of dental calculus, stains,pellicle, and other oral debris is significantly increased.

Thus, it would be highly desirable to provide an effective cleaning andpolishing agent which minimizes oral hard tissue damage. As has beenindicated, a variety of compounds are known which clean well but whichdo not polish, or which polish well but do not clean satisfactorily. Theaforesaid Ser. No. 374,257 application discloses that zirconium silicatehaving a particular particle size distribution may be employed as adental prophylaxis cleaning and polishing agent capable of achieving thedesired cleaning and polishing performance. In particular, the saidapplication describes a zironium silicate composition having particlesdistributed in three different levels, namely, a first level of up toabout 20 microns particle size, a second level of from about 20 up toabout 50 microns, and a third level of from about 50 up to about 70microns. In preferred practice, the said levels are combined in a composition having percentage ratio ranges of about 10-50% in the firstlevel, 525 in the third level, and the balance in the second level. Thesmaller particles of the first level are provided primarily to carry outa polishing function and in order to remove pellicle from oral hardtissues (i.e., enamel, dentin, and cementum); the particles of thesecond level are provided in order to clean and to remove stain; and theparticles of the third level are provided for cleaning non-organicrestorative materials (e.g., metal fillings, amalgams, inlays, and thelike) and for removing severe stains [e.g., green stain and stannousfluoride (SnF pigmentation].

In accordance with the present invention, it has been found that a newand even more effective dental prophylaxis cleaning and polishing agentmay be obtained by admixing z'irconium silicate with tin dioxide.Preferably, such an agent comprises at least about 50 and up to about 99% zirconium silicate and the balance tin dioxide. An especiallypreferred agent comprises a 9:1 weight ratio mixture of zirconiumsilicate and tin dioxide. Preferably, the zirconium silicate particlesare distributed throughout three levels substantially in accordance withthe percentage ratio ranges set forth in the aforesaid Ser. No. 374,257application. The tin dioxide particles substantially all fall within therange of up to about 3 microns and preferably of up to about 2 microns.An especially effective compo- 3 sition is obtained by employingzirconium silicate containing substantially no particles of less thanabout microns particle size.

The compositions of the present invention are capable of polishing oralhard tissue even better than the compositions of the said Ser. No.374,257 application. This result may be achieved without any diminutionin the cleaning capabilities of the composition. Another advantage ofthe zirconium silicate-tin dioxide cleaning and polishing compositionsof the present invention is that when they are employed in carrying outdental prophylaxis treatments, dental handpiece wear is reduced relativeto certain other cleaning and polishing compositions. Moreover, thecompositions of the present invention, when provided in paste form, areeasier to use and handle than certain other cleaning and polishingcompositions.

The aforesaid U.S. Patent No. 3,257,282 describes prophylactic pastecompositions comprising zirconium silicate as a cleaning and polishingagent and a fluoride-containing 'anticariogenic adjuvant. The saidapplication teaches that the utilization of zirconium silicate as acleaning and polishing agent in a dental prophylaxis compositionmarkedly enhances the effectiveness of anticariogenic adjuvantscontained in such compositions. It has been found, and forms a furtheraspect of the present invention, that the zirconium silicate-tin dioxidecompositions of the present invention likewise enhance the effectivenessof anticariogenic adjuvants contained in a therapeutic prophylacticpaste composition and in some instances are even superior tocompositions containing zirconium silicate alone.

It is, therefore, a primary object of the present invention to provide anew and improved dental prophylaxis composition comprising an admixtureof zirconium silicate and tin dioxide.

A related object of the present invention is to provide a dentalprophylaxis composition comprising zirconium silicate and tin dioxide ofdefined particle size ranges and distributions.

Yet another object is to provide an agent for dental prophylaxis thateffectively removes the most difficult enamel stains and pigmentationswhile minimizing loss of oral hard tissue.

A further object of this invention is to provide a dental prophylaxisagent adapted to polish all accessible tooth surfaces to a high lusterwhile eifectively cleaning such surfaces.

A still further object is to provide a dental prophylaxis agent adaptedfor cleaning and polishing oral hard tis- SlleS in order to render themless receptive to the retentron of dental calculus, plaque, and otheroral debris such as pellicle.

Another object is to provide a dental prophylaxis composition suitablefor admixture with a fluoride-containmg antlcariogenic adjuvant in orderto produce a therapeut1c (i.e., anticariogenic) dental prophylaxismixture.

Yet another object is to provide a dental prophylaxis composition whichis easier to handle and use in comparison with prior art prophylacticcompositions, and which in use does not produce objectionable dentalhandpiece wear.

A further object is to provide new dental prophylaxis methods adapted toclean and polish teeth effectively and, in addition, to reduce theincidence and severity of dental caries.

These and other objects, advantages, and features of the presentinvention will hereinafter appear, and, for purposes of illustration,but not of limitation, exemplary embodiments of the present inventionare hereinafter described in detail.

Formulation, characteristics, and manner of use In accordance with thepresent invention, it has been found that mixtures of zirconium silicateand tin dioxide exhibit optimal cleaning and polishing characteristicsfor use in dental prophylaxis. It has also been found that when aneffective amount of a fluoride-containing anticariogenic adjuvant isadmixed with such a zirconium silicate-tin dioxide mixture, a superiortherapeutic (i.e., anticariogcnic) prophylaxis composition is obtained.

The size of particles in a cleaning and polishing composition can beexpressed in a number of different ways, one of the most common of whichis mean diameter, i.e., the diameter above which one-half of theparticles are larger and below which one-half are smaller. Ashereinafter utilized, the term particle size refers to a mean diametervalue.

The dental cleaning and polishing agents of the present inventionpreferably comprise at least about 50% and up to about 99% ZrSiO andbalance SnO (i.e., a 99:1l:l ZrSiO SnO weight ratio range). An optimalpreferred range is at least about and up to about 92.5% ZrSiO, andbalance SnO (i.e., a 12.33:l-3:1 ZrSiO SnO weight ratio range). Thepreferred agent of the present invention comprises ZrSiO and 10% SnO(i.e., a 9:1 weight mixture of ZrSiO and SnO The zirconium silicateparticles are preferably distributed over three defined levels, namely,a first level of up to about 20 microns particle size; a second level offrom about 20 microns up to about 50 microns particle size; and a thirdlevel of from about 50 up to about 75 microns particle size. Preferably,the said levels are combined in a composition having percentage ratioranges of about 1050% in the first level; 5-25% in the third level; andthe balance in the second level. Substantially all of the tin dioxideparticles are of less than about 3 microns particle size and preferablysubstantially all are less than about 2 microns particle size. Whenzirconium silicate and tin dioxide having particles distributed inaccordance with the described ranges and distributions are admixed, asuperior cleaning and polishing prophylaxis agent is obtained.

In its generic sense, the zirconium silicate that is mixed with tindioxide differs from that set forth and described in the aforesaid Ser.No. 374,257 application only in that the upper level for zirconiumsilicate particles is about 75 microns rather than 70 microns asdisclosed in the aforesaid application, it having been found that thepresence of a minor amount of particles lying in the 70-75 micron rangeproduces no undesirable side effects when combined with the specifiedamount of tin dioxide, that is, the loss in polishing effectiveness thatwould be expected to result from the presence of a zirconium silicatehaving particle sizes above 70 microns is more than compensated for bythe increase in polishing capability attributable to the presence of tindioxide in the composition of the present invention.

The zirconium silicate component of the composition of the presentinvention is distributed throughout the said three levels in order toaccomplish the several different functions a satisfactory prophylaxiscomposition must be capable of performing. Thus, the particles of thefirst level (i.e., the smallest particles) are provided primarily tocarry out a polishing function and in order to remove pellicle from oralhard tissues; the particles of the second level are provided in order toclean and to remove stain; and the particles of the third level (i.e.,the largest particles) are provided .for cleaning non-organicrestorative materials and for removing severe stain. As mentioned above,the tin dioxide particles are provided primarily in order to enhance thepolishing capability of the over-all composition.

An especially preferred zirconium silicate agent adapted for admixturewith tin dioxide comprises particles distributed in the range of about1075 microns, that is, substantially no particles of less than about 10microns particle size are included in the agent. Thus, a preferredzirconium silicate formulation finds the zirconium silicate particlesbeing distributed in a first level of from about 10 up to about 20microns; second level of from about 20 up to about 50 microns; and athird level of from about 50 up to about 75 microns, the percentageratio range for the zirconium silicate particles being about 10-50% inthe first level; 25% in the third level; and balance in the secondlevel. While it is preferable that no zirconium silicate particles ofless than about microns particle size be provided in the mixture,nonetheless, because of practical difficulties of obtaining a mixturethat is completely free of under 10 microns particles, acceptabletolerances permit up to about 1% zirconium silicate particles of lessthan about 10 microns in such a preferred composition.

Especially preferred zirconium silicate mixtures adapted to be mixedwith tin dioxide comprise zirconium silicate distributed in accordancewith the values given in Table I. This zirconium silicate is admixedwith an appropriate amount of tin dioxide'of less than about 3 micronsand preferably less than about 2 microns particle size.

The preparation of suitable particle size zirconium silicate and tindioxide may be accomplished by conventional milling and segregationtechniques. Basically, these techniques involve milling of zirconiumsilicate and tin dioxide ores, followed by standard screen sieving tosegregate the desired particle size (e.g., a standard 400 mesh screenretains approximately 95% of 3S: 3% micron particle size). The exactmode of preparation and segregation of particle sizes forms no part ofthe subject invention and substantially any acceptable preparationtechniques may be employed so long as the desired particle size rangesand distributions are obtained.

The zirconium silicate-tin dioxide prophylaxis compositions of thepresent invention may be applied in the oral cavity in an aqueous slurryform as a part of a conventional prophylaxis, although in some instances(e.g., in the treatment of silver amalgams and of gold inlays) thecomposition may be introduced directly to the area of treatment. Ingeneral, a minimum amount of water (e.g., parts per 100 parts cleaningand polishing composition) should be utilized for maximum cleaning, andmore fluid mixtures (e.g., parts water per 1-00 parts cleaning andpolishing composition) should be utilized for maximum polishing. Ofcourse, each treatment should be handled on an individual basis,depending upon the exigencies of the circumstances.

It should also be understood that various other materials (such asflavoring agents) may be added to the zirconium silicate-tin dioxidecleaning and polishing composition described herein, so long as suchcomposition is employed as the essential cleaning and polishing mediumin the prophylaxis treatment.

A particularly useful mode of application of the zirconium silicate-tindioxide cleaning and polishing composition of the present invention isin the form of a paste. Such a paste may be packed and distributed inany suitable container, but it is preferred that such a pastecomposition be packaged in collapsible tubes. A prophylaxis may be moreeasily and efliciently performed using a paste packaged in tube form.

A prophylactic paste composition would conventionally embody (inaddition to a zirconium silicate-tin dioxide cleaning and polishingcomposition) other conventional agents such as flavoring materials(e.g., oil of wintergreen, oil of peppermint, oil of spearmint, oil ofsassafras, oil of anise, and the like); sweetening agents (e.g.,saccharin, dextrose, levulose, sodium cyclamate, and the like); binders(e.g., water-soluble salts of cellulose ethers such as sodiumcarboxymethyl cellulose and sodium carboxymethyl hydroxyethylcellulose); natural gums (e.g., gum karaya, gum arabic, and gumtragacanth) as thickeners; humectants (e.g., glycols, glycerin,sorbitol, and other polyhydric alcohols); and coloring agents.

The composition of a typical prophylaxis paste and a method offormulation therefor are given in the following Example.

Example I Ingredient: Amount (percent by weight) ZrSiO 66.99 SnO 7.44Distilled water 7.44 Glycerin (USP) 6.89 70%Aqueous sorbitol solution(USP) 9.49

Sodium carboxymethyl hydroxyethyl cellulose 1.30 Sweeteners 0.04Coloring agent 0.13 Flavoring agent 0.28

100.00 The distilled water is placed in a stainless steel mixing dish,and the sweetener (e.g., saccharin) is first dissolved in the water andthereafter the sorbitol, coloring agent, and flavoring agent are addedand thoroughly mixed. Tin dioxide is slowly added to the mixture andmixed well until all lumps are dispersed. Thereafter, zirconium silicateis added and is also mixed until the paste has a smooth consistency. Theglycerin is measured and placed in a separate container and the sodiumcarboxymethyl hydroxyethyl cellulose is added thereto and mixed in orderto form a binder composition. The binder composition is slowly added tothe zirconium silicate-tin dioxide-containing mixture and the resultingcombination is stirred until the binder is well dispersed throughout thepaste mixture and has undergone hydration. The paste is then deaeratedand may be tubed in a conventional manner.

Manner of use A typical method of application for a prophylactic dentalpaste composition produced in accordance with the present invention isgiven in the following example.

Example II The following procedure is preferred for thorough cleansingand polishing of the teeth on an annual or semiannual basis as required.Each tooth is thoroughly scaled in order to remove all calculus and softdebris. After scaling is completed, the buccal-labial surfaces of themaxillary right quadrant are polished using a soft rubber cup and anexcess of prophylactic paste (which may either be squeezed from a tubeas needed or which may be formulated by the dentist or dental hygienistas desired). Each surface of the tooth is treated for at least tenseconds. Then the lingual surfaces of the maxillary right quadrant arecorrespondingly treated. Unwaxed dental floss (which may be supplied inkit form with the prophylaxis paste) is used in all interproximals andpreferably is utilized with an excess of the prophylactic paste. Thepatient may be allowed to rinse thoroughly with water any time duringthe treatment.

After rinsing, the lingual one-half of the maxillary left quadrant ispolished and the patient is allowed to rinse. The bucco-labial one-halfof the maxillary left quadrant is polished, but the patient is notallowed to rinse until all of the interproximal contacts have beencleaned and polished with the unwaxed dental floss. The buccal andlingual surfaces of the mandibular right molars and bicuspids are thanpolished. Unwaxed dental floss is used in the interproximals beforerinsing.

The mandibular anterior teeth are polished next, both labillary andlingually, and the interproximal areas are polished with the unwaxeddental floss before rinsing is allowed. The buccal and lingual surfacesof the mandibular left molars and bicuspids are then polished, theinterproximals are dental flossed, and the patient is allowed to rinse.The occlusal surfaces and all pits and fissures the brushing so that theloss of weight attributable to the prophylaxis can be measured.

The dentin loss caused by the zirconium silicate-tin dioxide compositionof the present invention and by various commercially availableprophylaxis compositions were determined in accordance with thepreviously described method for both human and bovine dentin. Thesevalues are reported in Table 11. Human and bovine enamel loss data wereobtained in a similar manner and are then polished with a stiff bristleprophylactic brush are also reported in Table ii.

TABLE II.'SUMMARY OF ENAMEL AND DENTI'N ABRASION DATA OBTAINED \VITHVARIOUS PROPHYLACTIC PASTE COMPOSITIONS Enamel Abrasion Dentin AbrasionCleaning and Polishing Composition Human Bovine Human Bovine EnamelEnamel Dentin Dentin e) e) e) e) Zirconium silicate, tin oxide 27. 0614.27. 6015. 65 134. 65:13. 3 186119. Zirconium silicate 26. 565:3. 26 23.1013. 65 169. 4120. 6 178. :15. 5 Lava pumice"... 41. 5515. 58 481816.03222. 6117. 8 249. 4119. 5 Coarse pumice. 49. 4117. 54 40. 2117. 92 251.7111. 8 278. 2114. 7 Fine pumice. 50. 7018. 41. 2316. 37 245. 45:18. 4294.2127. 4 Flour of pumice 53. 9316.23 39.3416. 93 195.41 8. 0272.2117. 7 Calcite 34. 5813. 84 39. 5616. 89 150. 4119. 1 143. 05:24. 1Calcite-pumice 23. 7412. 82 26. 8515. 32 127. 2111. 4 144. 2129. 6Quartz-calcite 22 7813. 54 20. 3613. 23 138. 0114. 0 100.4112. 9Anatase, pumice, quartz and ieldsp 24 6914. 62 29. 865:7. 56 151. 35:10.5 169. 9127. 7 Kaolinite-quartz. 20. 565:3. 24 28. 715:7. 42 175. 8132.1125. :14. 0 Quartz (extra fine 28. 3712. 29 40. 515:5. 43 179. 2119. 7229. 15:14. 1 Quartz-pumice 49. 2818. 37 41. 2319. 80 161. 55:20. 3 240.05:32. 6 Pumice-illite 36. 1413. 94 44. 685:5. 21 163. 95:13. 5 233.9121. 5 Pumice-feldspar 30. 7414. 20 28. :5. 81 121. 05:13. 9 162. 9122.5 Quartz 45. 2215. 60 39. 1316. 68 166. 75:14. 4 268. 8130. 1

A zirconium silicate composition in accordance with the teachings of theaforesaid Serial N 0. 374,257 application and the prophylactic paste.The patient is then allowed to rinse his mouth as thoroughly aspossible.

Enamel and dentin abrasion properties Zirconium silicate is a well-knownindustrial abrasive which is used for grinding and polishing glass andceramics. The extreme hardness and abrasion characteristics exhibited byzirconium silicate (e.g., a hardness number of 7.5 on the Mohs scale forcommercially available zirconium silicate of type used for grinding ofglass) would suggest to one skilled in the art that zirconium silicatewould seriously damage (i.e., abrade and scratch) oral hard tissues andwould thus be unsuitable for use as a constituent in a dentalprophylaxis cleaning and polishing composition. However, experimentalevaluations of the zirconium silicate-tin dioxide compositions of thepresent invention have revealed that such compositions may in fact besafely employed without removing substantial amounts of oral hardtissue. Tooth dentin is frequently found exposed at the surface of theteeth near the free gingival margin, particularly in clinical caseswhere the gingiva have receded. The abrasion of tooth dentin by aprophylaxis agent is much greater than the abrasion of tooth enamel bythe same agent, i.e., 10-100 times. Consequently, the dentin abrasion isconsidered to be of greater importance than the enamel abrasion, and theeffect of a cleaning and polishing agent on dentin is used as animportant criterion in the selection of suitable agents. The zirconiumsilicate-tin dioxide mixture utilized in accordance with the subjectinvention has a highly satisfactory dentin abrasion characteristic, afact which is quite surprising in view of the innate hardness of thezirconium silicate constituent thereof.

The method for determining dentin abrasion values for dental cleaningand polishing agents is as follows. The dentin portions are separatedfrom human central incisors, and each dentin portion is mounted in a lowmelting alloy, such as Woods metal, and is submerged in a slurry of thecleaning and polishing agent to be tested in a 3 carboxymethyl cellulosesolution. An automatic toothbrush is arranged so that it can be movedback and forth across the surface of the submerged portion of thedentin, and the pressure of this toothbrush is adjusted to grams. Thetooth dentin is subjected to the brushing action for 50,000 doublestrokes, and removed from the slurry. The dentin portion is weighedbefore and after The data of Table II verify that the compositions ofthe present invention may be safely employed in carrying out dentalprophylaxis treatments.

Enamel polishing properties The enamel polishing properties of thezirconium silicate-tin dioxide prophylaxis compositions of the presentinvention have been compared with various commercially available dentalprophylaxis agents and pastes. The polishing agents and pastes wereevaluated in accordance with the so-called prophylaxis cup polishingprocedure. In accordance with this method, the lingual surfaces offreshly extracted maxillary anterior teeth are reduced with the aid of adiamond disc, and the teeth are mounted by means of a low melting alloy,such as Woods metal, on hexagonal jigs constructed so as to fit themovable stage of a reflectometer. The exposed labial surface of eachtooth is mounted in such a manner that the height of the contour is asuitable distance above the base of the jig. Throughout the procedure,care is taken to ensure that the teeth do not become dry in order toprevent damage of the tooth tissues. The exposed enamel surface is thendulled by exposing it to 0.10 percent hydrochloric acid (pH 2.2) for 30seconds. Any acid remaining on the tooth surface is neutralized byimmediately transferring the tooth to a saturated sodium carbonatesolution for 30 seconds. The tooth is then rinsed with water and blotteddry.

The maximum reflectance of the dulled tooth surface is determined bymeans of a reflectometer especially adapted to detect the changes in thedegree of polish of the enamel surface. The reflectometer is constructedso that the enamel is exposed to a beam of polarized light, and theamount of light reflected from the enamel surface is determined by aphotoelectric cell which in turn activates a galvanometer. The smootherthe enamel surface, the smaller the amount of diffused and absorbedlight and, hence, the higher the galvanometer reading.

After the maximum reflectance of the dulled tooth is determined, thetooth is polished through the use of a dental engine, conventionalhandpiece, and a rubber prophylaxis cup, the speed of the engine beingheld constant at 5000 r.p.m. The handpiece is permanently mounted so asto ensure equalized pressure. After the tooth has been polished forexactly 30 seconds with a slurry of the experimental prophylaxis pasteor agent, the enamel surface is rinsed with water so as to remove anyresidual particles of the cleaning and polishing agent, and thereflectance of the enamel surface is again measured with the toothlocated in exactly the same position as that used to obtain the dullreading. The change in the amount of reflectance between the dulled andthe polished enamel surface is taken as a measure of the degree ofpolish imparted by the prophylaxis treatment.

In order to express all measurements in terms of a recognized standardpolishing agent, each series of tests includes a treatment of the teethwith a specific sample of dry calcium carbonate (#300; Wittaker, Clark,& Daniels Co.) as a reference standard, and all data are expressedrelative to this agent in terms of a polishing ratio.

Polishing ratios obtained for the composition of the present inventionand for the various commercially available agents and pastes are givenin Table III, which also contains a percent superiority figure for thecompositions of the present invention.

TABLE TIL-COMPARATIVE POLISHING PROPERTIES OF VARIOUS DENTAL PROPHYLAXISAGENTS AND PASTES more fully set forth and described in Cooley et al.US. Patent No. 3,151,027, involves the use of polyester plastic blocksspecifically designed for use in an electric toothbrushing machine. Theblocks are ground smooth, washed, and dried, and a thin coat of blacklacquer is carefully applied to the surface of the block. The blocks arethen inserted in the toothbrushing machine and brushed with variouscleaning and polishing compositions for a set number of strokes at aconstant pressure. Reflectance measurements of the blocks are obtainedwith a reflectometer, all measurements being expressed relative to acalcium pyrophosp-hate standard. The results are expressed as cleaningscores on a scale of from 0 to 6.5, a higher value indicating a greatercleaning ability.

Polishing ratios (relative to a CaCO standard) and cleaning scoresobtained in the foregoing manner for various zirconium silicate-tindioxide mixtures are given in Table V. These mixtures range from a 100%zirconium silicate composition to a 100% tin dioxide composition.

TABLE V.SUMMARY 0F CLEANING AND POLISHING DATA PERTINENT TO RATIO OFZrSiOl TO SnOz Polishing Cleanin and Polishin A cut Cleaning andPolishing Agent Polishing Superiority g g g Pohshing Cleaning Rat)(Percellt ZrSiO4SnOi Percent by Weight Ratio Score Superionty) RatioZirconium silicate, tin dioxide 22. 9 Zrsloi S1102 Zirconium silicate18- 58 1:0 100.0 0. 0 18.58 5. 53 Q t -n a 63 2 9911 99.0 1. 0 21. 27 5.56 Pumice-1111mm 23 .5:2. 5 97. 5 2. 5 21. 4s 5. 53 P c e p 154-1 =195.0 5. 0 21.48 5 56 Kao it -q 88 5 30 .5; 7. 5 92. 5 7. 5 23. 97 5. soAragoniteealcite w 56 8 9=1 90. o 10. 0 23. 31 5. 53 A s ca c 37 5 17:385. 0 15. 0 23. 43 5. 55 Calcite 1 8 9 411 so. 0 20. 0 23. 02 5.60 t -p56 4 3:1 75. 0 25. 0 23. 22 5. 53 Quartz-calcite 59 3 111 50. 0 50. 022. 5. 53 gnatastiriurniceuartfi-fellspar 1 2&0 75,0 22 o 3 g uartzao-mon mori oni e Montmormomtefluartz 2' 67 753' 6 35 0.1 0. 0 100. 0 21.15 2. 13 Al(0H)a-pl1ml0c 10. 115. 3 Quartz-teldspar 7. 74 194. 4

A zirconium silicate composition in accordance with the teachings of theaforesaid Ser. No. 374,257 application.

Metal polishing properties In addition to being an excellent agent forpolishing oral hard tissues, the zirconium silicate-tin dioxidecompositions of the present invention exhibit superior polishingcapabilities when employed to polish dental restorative materials, suchas silver amalgam and gold, as verified by the following experimentalevaluation.

Gold and amalgam restorations were polished in the previously describedmanner, with the maximum reflectance being determined before and afterthe polishing treatment. Determinations were made for: (l) a zirconiumsilicate-tin dioxide agent produced in accordance with the presentinvention; (2) a zirconium silicate composition produced in accordancewith the teachings of the aforesaid Ser. No. 374,257 application; and(3) a mixture of zirconium silicate plus 10% stannous silicate (Sn SiOThe increase in reflectance (in absolute reflectometer units) obtainedwith these agents for gold and silver amalgam is given in Table IV. Thedata of Table IV verifies the high level of polishing eflectiveness ofthe compositions of the present invention for use on restorativematerials.

TABLE IV.POLISHING OF METAL RESTORATIONS Net Increase in Polishing UnitsCleaning and Polishing Composition Cleaning and polishing properties ofvarious ZrSiO -SnO mixtures The cleaning capability of a prophylaxispaste composition may be experimentally evaluated 'by means of acleaning grade test. This test, the procedure of which is The data ofTable V verify that superior cleaning and polishing results are obtainedwith the zirconium silicatetin dioxide mixture comprising at least about50% and up to about 99% ZrSiO and balance SnO (i.e., a 99:1-lz1 ZrSiO-SnO weight ratio range). An optimal preferred range is at least about75% and up to about 92.5% ZrSiO and "balance SnO (i.e., a 12.33zl-31lZrSiO -SnO Weight ratio range). The preferred mixture of the presentinvention comprises ZrSiO and 10% SnO (i.e., a 9:1 weight mixture ofZrSiO and SnO Dental handpiece wear An especial advantage of theimproved cleaning and polishing compositions of the present invention isthat the dental handpieces used in performing prophylaxis treatments isminimized, as shown by the following experimental evaluation.

Handpiece wear measurements throughout a series of three prophylaxistreatments were obtained for four different prophylaxis compositions.Before the first treatment and at the end of each successive treatment,the (1) loss in shoulder diameter of the prophy angle; (2) loss indiameter of the angle lip; (3) loss in diameter inside screw; (4) lossin weight of screw cap; and (5) loss in weight of shaft and gear weremeasured. The four prophylactic compositions evaluated were: (1) azirconium silicate cleaning and polishing agent produced in accordancewith the teachings of the aforesaid Ser. No. 374,257 application; (2) azirconium silicate composition produced in accordance with the said Ser.No. 374,257 application, but having substantially no particles of lessthan 10 microns particle size; (3) a 9:1 weight ratio of composition (1)and tin dioxide; and (4) a 9:1 weight ratio of composition (2) and tindioxide. The latter two compositions fall within the generic scope ofthe subject invention, with composition (4) being a preferredcomposition. The data obtained in this manner are reported in Table VI.

TABLE VI.SUMMARY OF DATA CONCERNING EFFECT OF VARIOUS PROPHYLACTIOPASTES UPON THE WEAR OF PROPHY ANGLES Loss in Loss in Loss in Loss inLoss in Cleaning and Polishing Composition Treatment Diameter atDiameter Diameter 7 Weight of Weight of No. Shoulder at Lip (in.) InsideScrew Cap Shaft and (in.) Screw (in.) (mg) Gear (mg) Composition (1)ZrSiO 1st 0. 0005 0. 0035 0. 0005 5. 3 7.2 0. 0020 0. 0005 0. 0005 1. 55. 7 0. 0020 0. 0000 0. 0005 3. 2 7. 6

Total 0. 0045 0. 0040 0. 0015 10. 20.

Composition (2) ZrSiO l0 0. 0010 0. 0020 0.0010 5.4 2. 5 0.0010 0. 00100. 0010 5. 7 3. 3 0. 0005 0. 0005 0. 0020 2. 0 5.

Total 0. 0025 0. 0035 0. 0040 14. 0 ll. 0

Composition (3) 9:1 ZlSlOrSXlOg 0.0005 0.0010 0.0005 2. 0 1. 7 0. 00100. 0020 0. 0000 1. 6 3. 6 0. 0000 0. 0010 0. 0000 3. 4 5. 3

Total 0. 0015 0. 0040 0. 0005 7. 0 10. 0

Composition (4) 9:1 ZrSiO -SnO (ZrSiO 1st 0. 0010 0. 0030 0. 0005 3.6 3.0 p) 2nd 0. 0010 0.0000 0.0010 0. 8 l. 1 3rd 0. 0000 0. 0000 0. 0010 0.5 0. 3

Total 0. 0020 0. 0030 0. 0025 4. 0 4. 4

The data of Table VI demonstrate that the compositions of the presentinvention, and particularly the preferred composition of the presentinvention may be employed without excessive dental handpiece wear.Moreover, this attribute is achieved without any loss in cleaning andpolishing effectiveness.

Therapeutic prophylactic pastes As previously indicated, the zirconiumsilicate-tin dioxide cleaning and polishing agent of the presentinvention also functions as a compatible carrier for anticariogenicadjuvants in therapeutic (i.e., anticariogenic) prophylactic pastecompositions. Preferably, the adjuvant should be presented in the formof fluoride-containing compounds capable of supplying fluoride andstannous ions or combinations thereof, for example, with an additionalcomponent, such as zirconium ions or germanium ions, in biologicallyavailable form.

The preferred adjuvants are stannous fluorozirconate (SnZrF stannousfluoride (SnF and complex zirconium-germanium fluorides [e.g., Zr(GeFZ'rOGeF Ge(ZrF ZrGeF ZrGeF and ZrOGe Stannous fluorozirconate and theindicated complex salts appear to be the best anticariogenicfluoride-containing adjuvants now known to the dentifrice arts,especially by virtue of the absence of objectionable taste, lack ofenamel pigmentation, freedom from damaging gingival tissue, andincreased anticariogenic effectiveness obtainable therewith.

Other suitable adjuvants include water-soluble fluoride salts such asNaF, SnF KF, InF PdF FeF and UP, as well as more complex water-solublefluoride-containing adjuvants such as fluorosilicates, e.g., Na SiFother fluorozirconates, e.g., CaZrF Na- ZrF and K ZrF fluorostannites,e.g., NaSnF fluoroborates, e.g., NaBF fluorotitanates, e.g., NaTiF otherfluorogermanates, e.g., K GeF and mixed halides, e.g., SnClF and Sn ClFMixtures of suitable adjuvants may also be utilized. Another suitableadjuvant comprises a mixture of a fluoride salt and an active phosphatecompound as set forth and described in applicants co-pending UnitedStates patent application, Anticariogenic Comopositions and Methods,Ser. No. 535,022, filed Mar. 17, 1966.

In general terms, where the foregoing essential ingredients are used informulating a therapeutic prophylactic paste composition, fluoride ionis employed at an effective and non-toxic level, usually within a rangeof from about 1 to about by weight of the composition. When SnF or SnZrFare utilized, such salts are preferably employed at a level of about 8%and respectively (i.e., about 8% SnF supplies about 3% fluoride ion andabout 30% SnZrF supplies about 10% fluoride ion). The compatiblezirconium silicate-tin dioxide cleaning and polishing mixture isemployed within a range of from Example III Constituent: Percent byweight ZrSiO 63 S1102 7 snzrr 2o Liquids 10 Such a therapeuticprophylactic paste may conveniently be formulated and prepared fordistribution and use in tube form in accordance with the general methodof Example I, above.

However, in many instances, because of the loss of anticariogeniceffectiveness attributable to the tendency of stannous ion-containingmaterials to oxidize and hydrolyze over time in an aqueous environment,it may be desirable to formulate the prophylactic paste just prior toapplication. This may be accomplished by adding the fluoride-containinganticariogenic adjuvant at the last minute to a prophylactic basecontaining the zirconium silicate, tin dioxide and other prophylacticpaste constituents. The following example is illustrative of this mannerof practicing the subject invention.

Example IV A prophylactic base having the following constituents wasformulated in a conventional manner:

Constituent: Percent by weight ZrSiO 69.3 SnO 7.7 Bleaching agents(e.g., TiO 4.0 Binders (e.g., sodium carboxymethyl hydroxyethylcellulose) 0.22 Humectants (e.g., glycerin) 17.8 sweetening andflavoring agents 1.0

This prophylactic base may be formulated into a therapeutic prophylacticpaste by dissolving 0.3 gram of stannous fluoride in 1 milliliter ofdistilled water and by adding the aqueous solution thereby formed to 2.0grams of the foregoing base, giving approximately a 9% SnF (i.e., about4% fluoride ion) content to the resulting prophylac- 13 14 tic paste.{ks an alternative, 0.93 gram of SnZrF may be The same essentialprophylaxis treatment procedure may dissolved 1n 1.0 cc. of distilledwater, and the aqueous b l d hether a therapeutic i i -i i solution canbe added to 2.0 grams of the foregoing prophylactic base, givingapproximately a 24% SnZrF (i.e., about 9% fluoride ion) content to theresultant prophylactic paste.

Experimental evaluations of zirconium silicate-tin dioxide prophylacticpaste formulations as described herein indicate that the zirconiumsilicate-tin dioxide mixtures or a non-therapeutic prophylaxiscomposition is used. In addition to the excellent cleaning and polishingresults obtained with a non-therapeutic zirconium silicate-tindioxide-containing composition, the provision of a fluoridecontaininganticariogenic adjuvant in the composition permits the added benefit ofthe anticariogenic attributes function as effective fluoride andstannous ion compatible of fluonde'c?nlfa mmg for Teducmgfm' Inclcarrier vehicles. In order to assess the effectiveness of a denfie andhmltmg the seventy of dental canes to be material as a compatiblecarrier vehicle for anticariogenic achlevedadjuvants, one analyticaltechnique that is conventionally indicated y the fomgoing data, theinvention employed is a so-called percentage availability determiclosedherein, in one of its aspects, provides a method for nation. reducingthe solubility of the oral hard tissue comprising Percentageavailability refers to a comparison of an the application thereto of aprophylactic paste composiionic concentration level for a combination ofcarrier vetion formulated from a zirconium silicate-tin dioxide hicleand of adjuvant relative to the corresponding ionic cleaning andpolishing agent together with an effective concentration level for areference SOlUilOIl Of the adjuamount of a fluoride-containinganticariogeni adjuvant vant Without the carrier vehicle (e.g., anaqueous solution In addition, the present invention includes a w and ofthe adjuvant maintained at a reference ionic concenimproved h d forcleaning and polishing the teeth Sufih as 1000 A f f comprising theapplication thereto of a prophylaxis comratio of the 1on1c concentrationlevel for the combination Position comprising Zirconium Silicate and tindioxide carrier vehicle and stannous fluoride which analyzes 900 p.p.m.fluoride concentration compared to a reference ployed m a professionalProphylaxls a prophylaxls solution of stannous fluoride at 1000 p.p.m.fluoride ex- P P dental} oflic? by dentlst or dental hibits a 90%availability insofar as ability to provide s the Present mventlfm alsoencompasses use of aqueous fluorid i is concerned) such pastes on anon-professional self-administered home Table VII gives exemplarypercentage availability data 11 s for fluoride and, in some instances,stannous ions for While the subject invention has been described withvarious fluoride systems, i.e., (1) sodium fluoride (NaF) reference tocertain exemplary embodiments, it should at 1000 p.p.m. fluoride ion;(2) NaF at 1000 p.p.m. 1111- be understood that various changes,modifications, and Wide P 10% mollcsodium dihydrogen phosphatealterations may be effected in the materials utilized, in the z diSiannolls fluoride z) at 1000 P-P- proportions of materials, and in themanners of formulatfluoride ion; (4) SnF at 1000 p.p.m. fluoride ionplus ing the compositions, without departing from the spirit 10%NaHzPOai 8% SnFz; and (6) 8% S111: 8% and the scope of the subjectinvention, as defined in the NaH PO and for several cleaning andpollshing comappended claims positions, i.e., (l) a zirconium silicatecleaning and pol- Whatis claimedis,

ishing composition obtained in accordance with the teach- L A d em a1propl'lylaxis composition for cleaning and ings of the aforesaid Ser.No. 374,257 application; (2) composition (1), but with all zirconiumsilicate particles pohshmg teeth 9 mpr 18mg as a cleaning i i icomponent a mlxture of uncoated zirconium silicate,

of less than 10 microns removed; (3) a 4:1 weight mixture of zirconiumsilicate and tin dioxide (i.e., a 20% uncoated tm dloxlde, S1102 Wheremthe S 0 ifi 4 a 9: Zirconium silicatefin zirconium silicate, ZrSiO has adistribution of mean diid mixture 10% 0 and 5 a 19;1 weight ameterparticle sizes 1n the range of up to about 75 mixture of zirconiumsilicate and tin dioxide (i.e., a 5% microns and the tin dioxide, 2, s adistribu ion of SnO mixture). mean diameter particle sizes in the rangeof up to about TABLE VIL-SUMMARY OF PERCENTAGE AVAILABILITY DATA PercentAvailability with Various Abrasive Systems Composition (1) Composition(2) Composition (3) Composition (4) Composition (5) ZrSiOr ZrSi04 l0u4:1 ZISlOq-SILO: 9:1 ZI'SlO4-S11Oz 19:1 ZISlO4-Sll0z Fluoride SystemConcentration Tin. Fluoride, Tin, Fluoride, Tin, Fluoride, Tin,Fluoride, Tin, Fluoride, Perwnt Percent Percent Percent Percent PercentPercent Percent Percent Percent The data of Table VII demonstrate thatthe zirconium 3 microns and wherein the zirconium silicate, ZrSiO issilicate-tin dioxide compositions of the present invention provided insaid mixture at a level of at least about 50 exhibit a high level ofstannous and fluoride ion comand up to about 99%, by weight of saidmixture, the patibility which is in many instances higher thancorbalance of said mixture being tin dioxide, SnO responding valuesobtained with compositions comprising 2. A composition, as claimed inclaim 1, wherein said zirconium silicate alone as their cleaning andpolishing mixture comprises at least about and up to about components.75 92.5% zirconium silicate, ZrSiO 3. A composition, as claimed in claim1, wherein said mixture comprises about 90% zirconium silicate, ZrSiOand about 10% tin dioxide, SnO

4. A composition, as claimed in claim 1, wherein the zirconium silicate,ZrSiO has a distribution of mean diameter particle sizes in a firstlevel of up to about microns, in a second level of from about 20 micronsup to about 50 microns, and in a third level of from about 50 microns upto about 75 microns, the three levels being combined in a percentageratio range of about 10-50% of the first level, 52S% of the third level,and the balance of the second level, and wherein the tin dioxide, SnOhas a distribution of mean diameter particle sizes in the range of up toabout 3 microns.

5. A composition, as claimed in claim 4, wherein the tin dioxide, SnOhas a distribution of mean diameter particle sizes in the range of up toabout 2 microns.

6. A composition, as claimed in claim 4, wherein the zirconium silicate,ZrSiO has a distribution of mean diameter particle sizes .with thefollowing ranges:

Particle size range (a): Percentage range 7. A composition, as claimedin claim 6, wherein the zirconium silicate, ZrSiO particle sizedistribution conforms to the following values:

8. A therapeutic prophylactic paste composition comprising ananticariogenically effective and non-toxic amount of at least onefluoride-containing anticariogenic adjuvant and as a cleaning andpolishing component a mixture of uncoated zirconium silicate, ZrSiO anduncoated tin dioxide, SnO wherein the zirconium silicate, ZrSiO has adistribution of mean diameter particle Sizes in the range of up to about75 microns and the tin dioxide, SnO has a distribution of mean diameterparticle sizes in the range of up to about 3 microns, wherein thezirconium silicate, ZrSiO is provided in said mixture at a level of atleast about 50 and up to about 99%, by weight of said mixture, thebalance of said mixture being tin dioxide, SnO and wherein said mixtureis provided in the over-all composition at a level of about -80%, byweight of the over-all composition.

9. A composition, as claimed in claim 8, wherein the fluoride-containinganticariogenic adjuvant is provided in the over-all composition at alevel of from about l-15%, by weight of the over-all composition,calculated as fluoride ion.

10. A composition, as claimed in claim 9, wherein said mixture comprisesat least about 75 and up to about 92.5% zirconium silicate, ZrSiO 11. Acomposition, as claimed in claim 9, wherein the zirconium silicate,ZrSiO has a. distribution of mean diameter particle sizes in a firstlevel of up to about 20 microns, in a second level of from 20 microns upto about 50 microns, and in a third level of from about 50 microns up toabout 75 microns, the said three levels being combined in a percentageratio range of about 10-50% of the first level, 5-25 of the third level,and balance of the second level, the tin dioxide, SnO having meandiameter particle sizes in the range of up to about 3 microns.

12. A composition, as claimed in claim 11, wherein the tin dioxide, SnOhas a distribution of mean diameter particle sizes in the range of up toabout 2 microns.

13. A composition, as claimed in claim 11, wherein the zirconiumsilicate, ZrSiO has a distribution of mean diameter particle sizeswithin the following ranges:

Particle size (a): Acceptable percentage ranges 14. A composition, asclaimed in claim 13, wherein the zirconium silicate, ZrSiO particle sizedistribution conforms to the following values:

15. A method for cleaning and polishing teeth comprising the applicationthereto of a dental prophylaxis composition comprising as a cleaning andpolishing component a mixture of uncoated zirconium silicate, ZrSi0 anduncoated tin dioxide, SnO wherein the zirconium silicate, ZrSiO has adistribution of mean diameter particle sizes in the range of up to about75 microns and the tin oxide, S has a distribution of mean diameterparticle sizes in the range of up to about 3 microns and wherein thezirconium silicate, ZrSiO is provided in said mixture at a level of atleast about 50 and up to about 99% by weight of said mixture, thebalance of said mixture being tin dioxide, SnO

16. A method for cleaning and polishing teeth and reducing the incidtnceof dental caries therein comprising the application thereto of a dentalprophylaxis composition comprising an anticariogenically effective andnon-toxic amount of at least one fluoride-containing anticariogenicadjuvant and as a cleaning and polishing component a mixture of uncoatedzirconium silicate, ZrSiO and uncoated tin dioxide, SnO wherein thezirconium silicate, ZrSiO has a distribution of mean diameter particlesizes in the range of up to about 75 microns and the tin dioxide, SnOhas a distribution of mean diameter particle sizes in the range of up toabout 3 microns, wherein the zirconium silicate, ZrSiO is provided insaid mixture at a level of at least about 50 and up to about 99%, byweight of the mixture, the balance of said mixture being tin dioxide,SnO and wherein said mixture is provided in the over-all composition ata level of about 30-80%, by weight of the over-all composition.

17. A method, as claimed in claim 16, wherein the fluoride-containinganticariogenic adjuvant is provided in the over-all composition at alevel of from about ride ion.

Referencs Cited UNITED STATES PATENTS Kaemmerling et a1. 167-93 Malone'y151-308 Salzmann et a1. 167-93 Saul et a1. 167-93 1 8 3,151,027 9/1964Cnoley et a1 167-93 3,257,282 6/1966 Muhler 167-93 FOREIGN PATENTS462,610 1/ 1950 Canada. 180,531 1/ 1936 Switzerland.

RICHARD L. HUFF, Primary Examiner. LEWIS GOTTS, Examiner.

1. A DENTAL PROPHYLAXIS COMPOSITION FOR CLEANING AND POLISHING TEETHCOMPRISING AS A CLEANING AND POLISHING COMPONENT A MIXTURE OF UNCOATEDZIRCONIUM SILICATE, ZRSIO4, AND UNCOATED TIN DIOXIDE, SNO2, WHEREIN THEZIRCONIUM SILICATE, ZRSIO4, HAS A DISTRIBUTION OF MEAN DIAMETER PARTICLESIZES IN THE RANGE OF UP TO ABOUT 75 MICRONS AND THE TIN DIOXIDE, SNO2,HAS A DISTRIBUTION OF MEAN DIAMETER PARTICLE SIZES IN THE RANGE OF UP TOABOUT 3 MICRONS AND WHEREIN THE ZIRCONIUM SILICATE, ZRSIO4, IS PROVIDEDIN SAID MIXTURE AT A LEVEL OF AT LEAST ABOUT 50 AND UP TO ABOUT 99%, BYWEIGHT OF SAID MIXTURE, THE BALANCE OF SAID MIXTURE BEING TIN DIOXIDE,SNO2.